Gold alloy and method of making the same



Patented Oct 13 1925.

UNITED STATES No Drawing.

To all whom it may concern: Be it known that I, VICTOR D. DAVIGNON, acitizen of the United States, and a resident of Attleboro, in the countyof Bristol and State of Massachusetts, have invented an,

Improvement in Gold Alloys and Methods of Making the Same, of which thefollowing description, in connection with the accompanying drawings, isa specification, like characters on the drawings representing likeparts.

This application-is a continuation in part of my pending application,Serial Number 47,367, filed July 31, 1925.

My invention relates to alloys of precious metals, and particularly toalloys of gold containing aluminum, and to the process of making thesame. 7

The gold alloy now commonly used in the arts has as its characteristicconstituents gold and copper with appropriate base metals other thancopper to give it the requisite' -hardness, color and other desiredphysis cal'characteristics'. This gold-copper alloy,

while otherwise satisfactory, has the disadvantage of possessing arelatively high spe:

cific gravity; and it 1s among the objects of my invention to produce agold alloy of much lower specific gravity but with the same gold ratio,thereby enabling me to fab ricate articles of given size or volume witha smaller gold content that with alloys heretofore known to me.

In the arts gold is rated according to its carat, that is to say, 14carat gold, for example, contains 14 parts by weight of gold and 10parts by weight of base metal, a total of 24 parts, and any gold alloywhich contains 14 parts by weight of gold for each 24 parts by weight ofalloy will be rated as 14 carat gold regardless of the s ecific'grav-.ity of the alloy. Accordingly, by reducing the specific gravity of thealloy by my improved method, I obtain an alloy which for a given caratand volume will have less,

weight, enabling articles of given volume made from it to berated atthis given carat although in fact containing a smaller amount of gbldthan if made of prior known alloys. For these reasons, as the cost ofproducing an alloy is largely determined by its gold content, articlesof given volume made of gold of a given carat can be made at lessexpense with my improved alloy.

I have found that it is impossible to alloy gold with aluminum by priormethods of 1,557,431 PATENT" OFF I com) ALLOY AND mentor) or MARI-[HG gY Application flied September 4, 1925-, Serial No. 54,499.

producing gold l a'lloys and obtain homogene- I ous product which ismalleable and ductile enough to meetthe requirements of the goldsmithand which possesses the requisite characteristics for enabling articlesto be desirable properties in the attempted aluminum alloy I believe islargely due to the presence of oxidized aluminum in the alloy.

As distinguished from the prior gold- .copper alloys,my improved alloyhas as its distinguishing characteristics the presence of aluminum inamount sufficient materially to reduce the specific gravity of thealloy; the

alloy being malleable and ductile to a degree 'suflicient to meet theusual, requirementsgof the goldsmith; and the ingot when made-$3. myimproved method being workable by usual goldsmiths 'p'rocewes, and beinga substantially. homogeneous structure free from checks and blisters,thus permitting eflicient utilization of the alloy.

The desired degree of hardness and color or other physicalcharacteristics are obtained by the introduction of other base metals aswillhereinafter appear. l

As showing the efiectof the aluminum on the specific gravity of myimproved alloy I may make a 14 carat gold alloy in the proportions of 14parts by weight of gold, 6 parts by weight of copper, 3 parts by weightofzinc, and 1 part by weight of alluminum. The'efiect of the aluminum onthe specific gravity of the alloy can be appreciated when it is observedthat in this example the volume of the aluminum employed-is slightlygreater than 50% of the volume of the gold due to the relatively lowspecific gravity of the aluminum compared to that of gold.

to, the metals entering into the alloy are placed in the crucible orother container in which they are melted, preferably in inverse order oftheir specific gravities, which is to say that the aluminum, forexample, will be placed at the bottom of the crucible and the gold andother metals above it. The ciuci ble is then heated in a furnace to atemperature at which the metals become liquid, the mixture convenientlybeing stirred to mix the constituents which is facilitated by the factthat the metals of low specific gravity tend to rise through themetalsof higher p specific gravity,

During the pouring operation, and prefer ably during a periodimmediately preceding the pouring operation, I efliect prevention of theaction of'the air on the molten metals, for example, the crucible asuitable s flux which, when added; will melt and form a liquid layer atthe of the molten metal and pass out of the crucible simultaneously withthe stream of molten metal entering the mold, this example beingparticularly applicable in cases where the melting and pouring areefi'ected by use of the conventional t pes'of crucible and mold.Preferably the ux employed in this example consists of or contains asubstance which will effectively eliminate from the alloy substantiallyall aluminum oxide I as well as the oxides of copper andof other mymethod I preferably which for s surface of iih chloride and sodiumfluoride.

base metals such as zinc, nickel and silver,

mixture of the'two inthe proportionof 1 part, calcium chloride to- 2.parts potassium bifluoride. These substances I have found at thetemperature of the molten metal will not substantially volatilize at thetempera.-

,-ture; maintained, and consequently will eifec tivel maintain a .sealon the molten metal in t e crucible and about the stream of molten metalbeing poured into the mold.

Intheabove example of the practice of crucible in the form 0 and. ourthemetal into the molds a flux as remained on the metal ina molten statefor a short period, say about five minutes. Preferably the amount offlux will be suflicient to form on the metal in the crucible a la er ofabout One quarter of an inch in ess. When the metal is poured the,

thic flux which leaves the crucible with the stream of metal, owing toits low specific gravity, will form a layer or film about the stream ofmetal andwill'enter the mold with the metal, thus preventing action ofthe air on the metal. At the same time the flux efi'ects elimination ofaluminum oxide which I explain it does by dissolving from the metalwhile the latter is'liquid, any oxv ide which may be formed or present,and

thus confining the oxide to the layer of slag in thecrucible and aboutthe e ingot. In addition to calcium chlorideand potassium bifluoride Ihave also found as suitable for flux, cryolite, potassium chloride,sodium given Although in the example of fluxes ogen salts of alkalineearths, it is all are he by adding to the contents of v .alloy mayconsist 0i, about 58% gol :alununumand' 37 copper, in which ex-' add theflux to the 1 crystals or owder r the to be understood that I am notnecessarily limited to fluxes "so characterized, but that other fluxeswhich will eliminate aluminum oxide and form'a liquid seal preventingaceess of airto the molten metal may beusecL.

In the above example of the practice of my method I'havefound thatsatisfactory results will be secured by employing sub 'stantiallypurevirgin aluminum, as for example, the grade characterized by the trade ascommercially pure, if substantially free from substances such as lead,phosphorus, bismuth and arsenic, deleteriously affecting physicacharacteristics of the alloy. I

Itwill be understood that in the above ex ample other base metals thanthose already.

mentioned may be added for imparting special properties to the alloy,and that the content of aluminum may beivaried relatively to the goldcontent to produce alloys of difierent carat and difl'erent specificgravity.

the malleability' or other desired c In practice, the gold may run from25% .to

% and the aluminum content from 1% to 10% by weightof the alloy, theremaining base metal in the'usual case being wholly or largely copperexcept where-green gold (commonly an 18 caratproduct) is desired,

in which case the remaining base metal will be wholly or largelysilve'r. As an example of a desirable 14 carat commercial alloy, the

ample desired, a portionof the copper maybe replaced by'other base metalor metals such as zmc,n ickel, silveryetc'. In

,. the claims by base metal rendering the alloy malleable and ductile Irefer to such .metals as-copper, silver, etci, commonly employed asconstituents of gold alloys.

As an example of the practice, of my lGt method but without limitationthereto I may.

take a graphite crucible of the generally frusto-conical shape commonlyemployed in the art, say the one known to the trade as a #8-black lead 7crucible, which is about four inches in. diameter at the top and aboutseven andione-half' inches high, and place in the bottom of the cruciblescraps of sheet aluminum about the size of a dime in amountequal to 5troy ounces. Upon the aluminum I'now place a mixture of 5833 troy ouncesof gold in bar form and 36.27

troy ounces of copper in the form of small ing of a mixture of potassiumbifiuoride andcalcium chloride crystals, heretofore de-' on the moltenmetal. About five minutes after the flux has melted the crucibleisremoved from the'furnace and the contents of the crucible are pouredinto the mold in I a steady stream of aboutthe thickness of a leadpencil say five-sixteenths of an inch.

The mold for this purpose conveniently may be of iron with a moldchamber, in cross-section a rectangle of about A,, by 2 inches, andabout 10 inches long. The mold preferably is positioned to place thelong axis of the mold chamber at about degrees to the horizontal andwith the sides of the mold chamber of greatest width in vertical planes.

The metal is now allowed to solidify, after which the mold is opened andthe ingot removed. After the ingot has cooled it. is placed in a pickleconsisting of dilute sulphuric acid in the proportion of 1 part acid to20 parts water and allowed to remain in the pickle until the slag orscale covering its exterior is removed or "softened sufiiciently topermit removal by subsequent washing, after which the ingot is removedand washed and then may be subjected to the rolling or other operationsdesired.v

Although I have described for purposes of illustration several specificcompositions of my improved alloy and one particular way of practicin mymethod, it is to be understood that am not limited thereby to theparticular method, constituents or proportions thereof, or to theparticular apparatus described, but that within the S00 e 01E myinvention widedeviations maye made therefrom without departingfrom thespirit of my invention.

I claim: l

and ductile gold-copper alloy having not less than about 25% by weightof gold and a material proportion ofcopper and containing at least 1% byweight of aluminum. 2. A- gold-copper alloy having not less than about25% by weight of gold and a. material proportion of copper and contain-.

ing. at least 1% of aluminum, and being substantially free from oxidizedaluminum. 3. A substantially homogeneous malleable and ductilegold-copper alloy having. not less than about 25% by weight of gold anda material proportion of copper and containing from 1 to 10% by weightof aluminum.

' loy's having 'a material proportion of coper and containing d fr an om1 to v said container into a mold. 4. Maleable and ductile gold-copperal-.

from about 25% to 85%.

having from about 25% to 85% by weight of gold and from 1% to 10% byweight of aluminum, and containing, base metal rendering the alloymalleable and ductile.

6. A malleable and ductile alloy containing by weight, about 58%. ofgold, 5% of aluminum an'd37% of copper.

7. A malleable and ductile alloy contain ing by weight .about 58% ofgold, 5% of aluminum and ;lf(% of base metal includ-' ing a materialamount of copper.

8. That process of making a gold alloy containing a material proportionof aluminum which comprises melting the metals in a container, andeffecting sealing oi the molten metal from the action of the atmospherewhile pouring the metal into a mold.

9. That process of making a gold alloy a container, and efi'ectingsealing of the molten metal from the action of the atmosphere whilepouring themetal into a mold by effecting on the stream of molten metalbeing poured from the container into the mold a coating of flux capableof eliminating aluminum oxide. 4

10. That processof making a gold alloy containing a material proportionof aluminum, which comprises melting. the metals in acontainer andadding to the molten metals a flux having a halogen salt of an alkalineearth;

11. That process of making a gold alloy containing a material proportionof alumi num, which comprises melting the metals in a container andadding to the molten metals a flux which will eliminate aluminum oxide.

12. That process of making a gold alloy containinga' material proportionof aluminum, which comprises melting the metals in acontainer and addingto the molten metals V a flux comprising potassium bifluoride. 1. Asubstantially homogeneous malleable f 13. That process of making a goldalloy containing a material proportion of aluminum, which comprisesmelting the metals in a container and adding to the molten metals a fluxcontaining calcium chloride and po' tassium bifluoride."

14. That process of making a gold alloy containing a material proportionof alumimetal from the atmosphere, and pouring the molten'm'etal andflux simultaneously from 15. That process'of making argold alloycontaining a. mate'ral proportion, of alums num, which com rises meltingthe metals in i a container, addingto the metals 8. flux containing afusible halogen salt of an'alkaline earth in amount suflici'entfto'forma liquid layer on the molten metal efiective'to seal said metal from theatmosphere, and pouring .the molten metal and flux simultaneously fromsaid container'into a mold.

16. That process of making a gold alloy containing a material proportionof aluminum, utilizing a cruicble, a furnace" and a mold, whichcomprises placing the-metals in solid state in said crucible with thealuminum below the heavier metals, heating the crucible to render saidmetals liquid,

adding to said crucible after liquefaction of the metals a fusible fluxcontaining metallic salts capable of eliminating aluminum oxide,

' said flux being in amount suflicient to form In testimony whereof, Ihave signed .my 20 name to this specification.

VICTOR D. DAVIGNON.

